Considerable research has been undertaken for many years to understand how the human eye functions when receiving light and transmitting signals concerning that light to the brain. One of the areas of research has been in electroretinography, which is a study of the electrical potentials produced in the eye. It can be readily understood that because of the extreme sensitivity of the eye these measurements are difficult to obtain. Furthermore the results may be confused by potentials which are due to muscular activity, pain reflexes, etc. A general survey of the types of electrodes and procedures which have been used in the past may be found in the article by Riggs entitled "Electrophysiological Technique for Studying Visual Function in Man: A Historical Overview", J. Opt. Soc. Amer. 67, 1451-7(1977). As this article will show the most common procedure is to employ any of several types of contact lenses which are fashioned with a built in electrode lead which can be connected to a suitable device for the measurement of the potential. Each of the known contact lens electrode devices suffers from one or more of the following disadvantages:
(1) The electrode and contact lens assembly is large and frightens children. PA1 (2) The contact lens distorts the optics of the eye. PA1 (3) The electrode and/or the lens frequently scrapes the corneal epithelium. PA1 (4) The electrode and contact lens assembly must be made in several specific sizes for different patients. PA1 (5) The electrodes and contact lens assembly is expensive, is not disposable, and cannot be sterilized in an autoclave. PA1 (6) The contact lens assembly can abrade conjunctival sac tissues. PA1 (7) The contact lens assembly is often painful when in place. PA1 (8) Anesthetic must be used.
It is an object of the present invention to provide a corneal electrode for use in electroretinography which does not suffer from these disadvantages and which is capable of measuring the potential with at least the same degree of accuracy as that of the best of the prior art contact lens systems.
The novel features believed to be characteristic of this invention as set forth with particularity in the appended claims. The invention, however, both as to its organization and method of operation, together with further objects and advantages thereof may best be understood by reference to the attached drawings and to the following description.